Forty-year-old Guy Trilby discovers a loophole in the Golden Quill Spelling Bee which stipulates that participants must have not graduated from the eighth grade, allowing him to enter since he dropped out of middle school. He attends and wins a regional spelling bee, and progresses to the national competition after confrontations with both the parents of children and the spelling bee hosts. He is accompanied by Jenny Widgeon, a relatively unknown journalist hoping to make a story out of his participation in the bee. On the flight to the national spelling bee, Guy meets Chaitanya Chopra, a 10-year-old entrant in the bee who persistently attempts to befriend Guy. Upon his arrival in Los Angeles, Guy meets the director of the spelling bee, Dr. Bernice Deagan, who expresses anger at his participation in the bee and places him and his reporter in a cheap hotel. Guy learns that Chaitanya is staying in the same hotel, and takes him out one night to expose Chaitanya to the wilder side of life: stealing food, drinking, and hiring a prostitute to briefly “flash” Chaitanya.
In the bee, Guy actively tries to distract and disconcert his fellow competitors, at one point insinuating that he was sleeping with another contestant’s mother. Despite Dr. Deagan’s tampering with the word list to give Guy the most difficult words, he spells long, complicated words with relative ease, impressing and angering both parents and staff at the spelling bee, including the event’s founder, Dr. William Bowman. However, the parents petition for his disqualification and the resignation of Deagan. While researching Guy’s background, Jenny discovers that Bowman is Guy’s father. She reveals this to him and he admits that his prime motivation for entering the bee was to embarrass his father in revenge for abandoning him and his mother when he was a child. Soon before the final stage of the bee, Guy overhears Chaitanya and his father discussing his strategy to win, which is to befriend Guy so that he will allow Chaitanya to win out of guilt. Guy storms into the room and ends his friendship with Chaitanya, despite Chaitanya’s pleas that he genuinely wanted to be friends. They later sabotage each other: Guy burns Chaitanya’s study book, “Todd,” and Chaitanya files a false police report, accusing Guy of kidnapping a young girl.
Meanwhile, only ten competitors remain in the bee, and the pool is gradually reduced to just Guy and Chaitanya. When a contestant’s mother attacks Guy verbally and is subdued by the police on live television, Bowman is forced to intervene, to his embarrassment. Having accomplished his goal, Guy deliberately misspells a word in an effort to let Chaitanya win. To prove his friendship, Chaitanya also misspells his word, and they soon begin to argue. This escalates into a physical fight, and when Bowman attempts to intervene, Chaitanya accidentally hits him with a chair. Although the bee is briefly halted, Bowman allows it to continue after deciding that both Guy and Chaitanya acted in an equally embarrassing manner. Their standoff of deliberately misspelling words continues until Guy intentionally misspells Chaitanya’s word so that Chaitanya corrects him, thus causing Chaitanya to win the bee inadvertently. As Guy leaves, content, Chaitanya offers to give him half the winnings and names him co-winner of the bee. Guy writes a note to Bowman explaining his actions, which Bowman refuses to read until Guy reveals himself to be his son, and returns home. He resolves his conflict with Chaitanya by buying an old police car from an auction with his share of the winnings, and helping Chaitanya to chase down his school bullies.